Spring Add PreFlightRequestWebFilter

Similar to CorsWebFilter there should be a PreFlightWebFilter in Spring Framework that leverages the PreFlightRequestHandler API.

Related gh-26257 spring-projects/spring-boot#24541

Comment From: rstoyanchev

We could a default method to PreFlightRequestHandler. Would that work for you @rwinch?

default WebFilter asWebFilter() {
    return (exchange, chain) -> 
            CorsUtils.isPreFlightRequest(exchange.getRequest()) ? 
                    handlePreFlight(exchange) : chain.filter(exchange);
}